Laura Linney and Hattie Morahan are also joined by Patrick Kennedy, Hiroyuki Sanada, Phil Davis and Milo Parker in the new movie directed by Bill Condon

The cast for Ian McKellen's Sherlock Holmes film is shaping up nicely with the announcement that McKellen will be joined by Roger Allam (Endeavour) and his Vicious co-star Frances de la Tour.

Mr Holmes – which stars the 75-year-old actor as Arthur Conan Doyle's retired super sleuth – has just begun filming in London and the South Coast, reuniting McKellen with his Gods and Monsters director Bill Condon.

Set in 1947, the drama is based on Mitch Cullin's book A Slight Trick of the Mind and will depict an ageing Sherlock Holmes aged 93, returned from a journey to Japan where he witnessed the devastation of nuclear warfare. Based in a remote seaside farmhouse, the brilliant detective spends his days tending to his bees in the company of Munro and her young son, Roger.

With his famous mind palace diminishing, Holmes begins to rely on the boy as he revisits the unsolved case that sent him into retirement – and searches for answers to the mysteries of love and life before it's too late.

Yesterday evening McKellen tweeted the first picture of himself dressed in character as the ageing Holmes:

At the time of his casting, the British actor said: "Sherlock Holmes at 93 is retired, still solving mysteries: but here’s the sting – he also keeps bees. So many splendid actors have already played the part but none of them had Bill Condon directing. I’m the lucky one: and I’m excited."

Mr Holmes is a collaboration between BBC Films, See-Saw Films and AI, the production arm of Icon Films in the UK.